Spark-plug tester



H. L. OPSAHL.

SPARK. PLUG TESTER.

APFLICAUON man SEPT. 7. 192s.

1,878,484. Pante May 17,1921.

and

UNITED STATES.

PATENT oFFICE HARRY L. QPSAHL, 0F MINNEAPOLIS, MINNESOTA.. l

" SPARK-PLUG TESTER.

T0 all whom it may concern.: Y

Be it known that I, HARRY L OrsAHL, a citizen of the. United States, residing at Minneapolis, in the county ofv Hennepin and State of Minnesota, have invented certain new and useful Improvements in Spark- Plug Testers; and I do hereby declare the following yto be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it ap,

pertains to make and use the same.

` My invention has for its object to provide an extremely simple and highly efficient spark plug tester; and to this endV consists of the novel devices and combina- 'tions of devices hereinafter described and dened in the claims.

My tester is permanently attached to the plug where it may always be seen alone or in combination with the other plugs of the engine. In this way,it -is exceedingly easy to locate faulty plugs cui-t. s

In addition ,to testing Vplugs for grounds or partial ground and testing the strength of the spark circuit, the length of the electrode gap may be ascertained by the adjustable means of my tester.

The invention is illustrated in the Aaccompanying drawings, wherein like notations refer to like parts throughout the several views.

Referring to said drawings Figure 1 is a .side eleva-tion of the'spark plug with my tester operatively attached and its inoperative position shown in dotted lines; Y

Fig. 2 is a front elevation of the same;

Fig. 3 is a side elevation of a portion of plug with a slight modification of my tester attached.

The numeral et indicates an ordinary spark plug having a metal shell 5, an electrode terminal 6 with a thumb screw 6a, and spark electrodes 7. l

A strip of ribbon metal is bent together to form a spring testing finger 8 having a tip 8a, which coperateswith the metal shell 5 of the plug to form a pair of testing electrodes and an anchor arm 9 directly beneath said testing finger 8, the use of which we shall presently explain. The said folded metal strip, comprising the two above parts, is fas- Specifcaton of Letters Patent. i

or a bad ignition cirtened to the terminal o f the pluguthrough co-y inciding holes in its foldedv end byfmeans of the terminalthumb screw 6a. Thespringtension, in the folded end of the said strip,

serves -to bindV the thumb screw 6 against the threads ofthe terminal 6, thus prevent-- 10 carried by and fastened rigidly to th`e same by means of a small lock nut 10a on the inside ofvsaid arm. The screw 10 further passes through a hole in the testing finger 8 and is engaged by an insulated adjusting nut 11, which is operative to vary the distance of the finger tip 8a from theshell 5 Patented May 17,1921. v vApplication led September?, 1920. Serial No. 408,443. i i l of the plug. The said anchorarm acts-asV a base of resistance to effect this adjustment. rEhe modification of my device, shown in Figxj, consists simply in attaching the screw bolt 10 to the testing finger 8 and placing the adjusting nut11 on the inside of the anchor arm l9. i v Opemzfe'o/n..

inoperative dotted position, shown in Fig. 1, inwardly, until the gap between the `testing electrode 8a andthe shell 5 begins to spark. The length of this testing gap will be ,equal to the electrode gap of the plug. This is due tothe fact that electricity takes a path of least resistance and, when the two gaps are madefthe same, both will spark and not until then. f

If the plug is grounded, there will be no spark from the testing finger despite all adj j Y j so The testing finger 8 is adjusted from the justing, and, if partially grounded, only a very weak spark will be observed. yIn case of a weak or faulty ignitionfsystem, theV testers on lall ofv the plugs will show uniformly weak sparks. By-testing all of the plugs simultaneously, it` will be found exceedingly simple to discover the faulty ones, ascertain't'he strength of the spark, and, by examining the respective testing gaps, find the length of the corresponding electrode gaps.

The insulated adjusting nut 11 allows a` person to adjust'the testing finger 8, with out getting a shock.

My device is, of course, always attached tok a plug where it may readily be adjusted land thereof andV being attached to a spark plugV through this double thickness, the ends thereof further bent to vextend downwardly along the side of the spark plug in spaced relation, one end forming a testing electrode and the other end forming a base of resistance for adjusting said electrode toward and from the plug, and means for adjusting said electrode.

2. The `structure set forth in claim 1, the electrode arm being longer than and extendingrbelow the arm forming the base of resistance for adjusting the electrode arm.

3. A spark plug tester attached to a spark plug having a testing linger attached to the terminal of the plug cooperating with the shell of said plug to form a pair of testing electrodes operative to test the plug and indicate the strength of the spark and the length of the electrode gap, an anchor arm also attached to the terminal acting as a base of resistance to adjust the testing finger from an inoperative to an operativeV position,

and an insulated adjusted nut engaging an adjusting screw to affect the same.

4;. A spark plug tester attached to the i terminal of a spark plug comprising two parts, both of which are bent Afrom a single strip of flexible metal,kone a spring testing finger coperating with the shell of the plug to form a pair of testing electrodes and the other an anchor arm acting as a base of resistance to adjust the testing finger from an idle to an operative position, and an insulated adjusting nut engaging an adjusting screw to affect the same, thev said device being operative to test the plug and indicate the strength of the spark and the length of the electrode gap. Y Y Y 5.`A spark plug tester attached to the terminal of aspark plug comprising two parts, both of which are bent from a' single strip of fieXible metal, the tension between the said two parts, near their fold, serving as a binder for the terminal thumb screw, one of said partsv being a yspring testing linger coperating with the shell of the plug to form a pair of testing electrodes and the other an anchor arm acting'as a base of resistance to adjust the testing finger from an idle to an operative position, and an insulated adjusting nut engaging an adjusting screw to affect the same, the said devicebeing operative to test the plug and indicate the strengthof-the spark and the length of the electrodeY gap. 1

In testimony whereof I aiix my signature. Y HARRY L. OPSAHL. 

